Europe’s first farmers replaced hunter-gatherers

Analysis of ancient DNA from skeletons
suggests that Europe’s first farmers were not
the descendants of the people who settled in the area after the retreat of the ice
sheets.

Instead, the early farmers probably migrated
into major areas of central and Eastern Europe about 7,500 years ago, bringing
domesticated plants and animals with them, according to new research from Mainz University,
UCL and the University of Cambridge, published online
in Science.

The researchers analysed DNA from
hunter-gatherer and early farmer burials, and compared those to each other and
to the DNA of modern Europeans. They conclude that there is little evidence of
a direct genetic link between the hunter-gatherers and the early farmers, and that
82% of the types of mtDNA found in the hunter-gatherers are relatively rare in
central Europeans today.

For more than a century, archaeologists,
anthropologists, linguists, and more recently, geneticists, have argued about the identity of the ancestors of Europeans living today. They have established that
people lived in Europe before and after the
last big ice age, and managed to survive by hunting and gathering. They also know
that farming spread into Europe from the Near East over the last 9,000 years,
thereby increasing the amount of food that can be produced by as much as
100-fold. But the extent to which modern Europeans are descended from either of
those two groups has eluded scientists despite many attempts to answer this
question.

Now, a team from Mainz
University in Germany, together with researchers from UCL and Cambridge, have found that the first farmers in central
and northern Europe could not have been the
descendents of the hunter-gatherers that came before them. But even
more surprisingly, they also found that modern Europeans couldn’t solely be the
descendants of either the hunter-gatherer alone, or the first farmers alone,
and are also unlikely to be a mixture of just those two groups.

“This is really odd”, said Professor Mark
Thomas, UCL Genetics, Evolution & Environment and co-author of the study. “For more than a century the debate has
centred around how much we are the descendants of European hunter-gatherers
and how much the descendants of Europe’s
early farmers. For the first time, we are now able to directly compare the
genes of these Stone Age Europeans, and what we find is that some DNA types
just aren’t there – despite being common in Europeans today.”

Humans arrived in Europe
45,000 years ago and replaced the Neanderthals. From that period on, European
hunter-gatherers experienced lots of climatic changes, including the last Ice
Age. After the end of the Ice Age, some 11,000 years ago, the hunter-gatherer
lifestyle survived for a couple of thousand years, but was then gradually
replaced by agriculture. The question was whether this change in lifestyle from
hunter-gatherer to farmer was brought to Europe
by new people, or whether only the idea of farming had spread. The new results from
the Mainz-led team seem to resolve much of this long standing debate.

“Our analysis shows that there is no direct
continuity between hunter-gatherers and farmers in Central
Europe,” says Prof Joachim Burger. “As the hunter-gatherers were
there first, the farmers must have immigrated into the area.”

The study identifies the Carpathian Basin
as the origin for early Central European farmers. “It seems that farmers of the
Linearbandkeramik culture immigrated from what is modern day Hungary around 7,500 years ago into Central Europe, initially without mixing with local
hunter gatherers,” says Barbara Bramanti, first author of the study. “This is
surprising, because there were cultural contacts between the locals and the
immigrants, but, it appears, no genetic exchange of women.”

The new study confirms what Joachim Burger´s
team showed in 2005; that the first farmers were not the direct ancestors of
modern European. Burger says “We are still searching for those remaining
components of modern European ancestry. European hunter-gatherers and early
farmers alone are not enough. But new ancient DNA data from later periods in
European prehistory may shed also light on this in the future.”